Update readme

Signed-off-by: Xuzheng Chang <[email protected]>

Author: Monokaix

README.md

@@ -9,19 +9,22 @@ Please refer to Helm's [documentation](https://helm.sh/docs/) to get started.
 
 Once Helm is set up properly, add the repo as follows:
 
-```console
+```shell
 helm repo add volcano-sh https://volcano-sh.github.io/helm-charts
 ```
 
-You can then run `helm search repo volcano-sh` to see the charts.
+You can then run `helm search repo volcano-sh` to see the charts. If you had already added this repo before, please run the following command to get the latest version.
 
+```shell
+helm repo update
+```
 
 **Install Volcano:**
-```
+```shell
 helm install volcano volcano-sh/volcano -n volcano-system --create-namespace
 ```
 
 **Uninstall Volcano:**
-```
+```shell
 helm uninstall volcano -n volcano-system
 ```